After spending some time in London and Pembrokeshire as tutor to the son of the Member of Parliament Pryce Campbell, he accompanied his young charge to Edinburgh University, where he took the opportunity to continue his own studies in divinity.
He mixed with all the stars of the Scottish Enlightenment while in Edinburgh, being particularly repelled by what he thought were the vulgar manners and conversation of the philosopher David Hume.
He returned to St Andrews and became, on 21 May 1772, just short of his 22nd birthday, joint professor of Greek (though his aged predecessor still monopolised the salary, leaving George the private tuition fees).
His lecture notes indicate his course was far more a cultural studies course – covering history, geography, literature, drama and philosophy – which is just as well, as it appears many of his students could not recognise the Greek alphabet.
On 3 May 1775, using family connections, he managed to have himself licensed to preach the Gospel by the Presbytery of Haddington, and soon afterwards began assisting the ailing Principal Tullideph in his parochial church of St Leonards.
In 1775, he was offered the living of Coldstream by the Earl of Haddington, a pupil of his father's, but he turned it down, preferring to stick with his duties in St Andrews.
In 1779 he was being urged by Principal Robertson to accept an offer by the Town Council of a post in Edinburgh, but he had reasons to think prospects were opening up nearer home, so he politely declined.
By 1799, it was clear that the principal of the university, his uncle Dr M'Cormick, was dying, and he was offered the chance to succeed him, but he turned it down as he would have lost money by having to give up his second charge minister's post for the less lucrative one of St Leonard's.
He was ordained an Elder on appointment as professor of Greek and ever since then had been returned as representative of the university, or of the presbytery, to the General Assembly of the Church of Scotland at its yearly meetings.
These saw themselves as enlightened Calvinists and Presbyterians who were prepared to compromise with the Government in many matters - in particular, over the issue of Patronage - but not on the spiritual independence of the Church.
He was a very sincere Calvinist and a proud Presbyterian, but did not take a gloomy view of the former, and accepted that landowners (the Heritors) who paid a Minister's salary had some rights in their appointment.
In 1782, when the Lord Advocate seemed to threaten him for his views that the usual address to the Crown was too political, he said The Church of Scotland is independent of any party and any Ministry; he cared not for the threats of the learned gentleman, and he might tell his friends in power that he had said so.
During the French Revolutionary Wars, he vigorously opposed a plan to get Parish Ministers to urge support for a voluntary levy, as compromising the political independence of the Church and unseemly for a pacific profession.
This was extraordinary for a man renowned as a British patriot - he expressed the hope "that this island will continue, to the latest ages, the fair seat of regulated freedom, of rational religion and public virtue"- and a Moderate (inveterate compromisers with the Government according to their enemies).
For instance, he argued strongly against Professor John Leslie who had written an Essay on Heat, which was thought to echo too closely some sceptical philosophic views of David Hume, and were therefore "destructive of religion".
Earlier, although he thought that the British Government could have handled the American Colonists with more conciliation, he was in no doubt they were rebels to a legitimate and beneficent King.
In 1798 The General Assembly issued "A Warning and Admonition to the People of Scotland" (against popular unrest) which was produced by a committee and strongly supported by Hill.
In his Ministry he was universally loved, according to Mr Cook, while anonymous letters (actually by Andrew M Thomson) suggesting that he worked the patronage system to his own, and his sons' advantage are dismissed.
Their son (Hill's nephew) was the Very Rev George Cook who served as Moderator of the General Assembly of the Church of Scotland in 1825.